1. Field of the Invention
The present invention relates generally to computer-aided methods and systems for manufacturing products in a high volume, automated, continuous process and, more particularly, to improved methods and apparatus for automatically positioning electronic dice within component packages.
2. State of the Art
Integrated circuit devices are well-known in the prior art. Such devices, or so-called xe2x80x9cdice,xe2x80x9d are normally designed to be supported or carried in a package having a plurality of pins or leads. The package serves as a carrier and as a heat sink and is normally square or rectangular in shape. The packages, which includes a cavity in which the integrated circuit die is placed, may be formed of metal, ceramic or plastic components. After the integrated circuit is secured in the cavity of the package, a component xe2x80x9clidxe2x80x9d is typically placed over an exposed surface of the circuit. A bottom surface of the lid includes a xe2x80x9cpre-formxe2x80x9d material such as epoxy or solder that is used to secure the lid over the circuit to provide a protective cover. The pre-form is cured by placing the package in a furnace.
Packaging unusable dice which must be scrapped after testing is inefficient and costly. Accordingly, the dice are often tested for continuity during the manufacturing process. This has been accomplished by placing dice in temporary packages and subjecting the assembled package to extensive testing, which includes burn-in and discrete testing. Discrete testing includes testing the devices for speed and for errors which may occur after assembly and after burn-in. Burn-in testing accelerates failure mechanisms such that devices which have the potential to fail later but which failure would not otherwise be apparent at nominal test conditions can be eliminated.
However, testing unpackaged dice requires a significant amount of handling. The temporary package must not only be compatible with test and burn-in procedures, but must also secure the die without damaging the die at the bond pads or elsewhere during the process. Bonds pads are conductive areas on the face of the die which are used as an interconnect for connecting the die circuitry to the package. The positioning of the die within the cavity of the temporary package is therefore critical since the placement of the die bond pads relative to the temporary package electrical interconnects must be properly aligned in order to subject the die to such extensive testing.
Precising die packaging includes mechanically locating a component in a precise position or placement. Various xe2x80x9cprecisingxe2x80x9d methods for this purpose are known in the art. However, there have been several problems associated with such precising methods and systems. For example, it has been difficult to position the die bond pads in electrical contact with temporary package electrical interconnects in an accurate and consistent manner so as to facilitate a high volume, continuous manufacture of temporary packages. Another disadvantage associated with the prior art is that the die is often destroyed upon contact with the temporary package. Moreover, a significant investment in the costly integrated circuit device is often lost when the positioning of the die within the temporary package is not properly aligned. Accurate placement and positioning of the die in the temporary package is thus critical to providing acceptable results.
One attempt to overcome the problems associated with the prior art has been to precise die and packages by mechanical fixturing. However, assembly tolerances used in mechanical fixturing techniques are often insufficient to prevent improper alignment. Mechanical fixturing also leads to damage of the die or temporary package. While such techniques have proven useful in improving the accuracy and reliability of the die placement, these techniques do not enable dice to be precisely positioned within temporary packages in a manner that allows production efficiencies capable of supporting large volume operations.
Accordingly, there remains a long-felt need in the semiconductor industry to provide for improved methods and apparatus for manufacturing integrated circuit temporary packages in a high volume, cost-efficient and reliable manner which includes automatically positioning integrated circuit dice within the temporary packages such that die bond pads are in electrical contact with temporary package electrical interconnects to allow extensive testing to be performed.
It is thus a primary object of the present invention to provide computer-controlled methods and apparatus for automating the positioning of integrated circuit devices or dice within temporary packages utilizing a high volume, continuous process.
It is another object of the invention to provide an automated apparatus for the positioning of electronic dice within temporary packages that is used in-line with other machines to facilitate formation of assembled packages which may then be subjected to continuity testing and the like.
It is yet another object of the invention to describe methods and systems for accurately positioning electronic dice within temporary packages in a reliable, cost-effective manner.
It is still another object of the invention to provide methods and apparatus for continuous positioning of integrated circuit dice within temporary packages in a production line while significantly reducing the percentage of dice and temporary packages in which continuity is not established.
Yet another object of the invention is to provide multiple inspections of the die and temporary package prior to, during and after placement of the die within the temporary package. By inspecting the die at various stages of assembly, dice which are not properly aligned or positioned can be repositioned to maximize the number of electrical contacts between the die bond pads and temporary package electrical interconnects.
It is still another object of the invention to preferably use multiple cameras to facilitate precise placement of the dice in the temporary packages in a continuous manner, thereby significantly enhancing the efficiency of the processing line and increasing the number of packages in which continuity is established.
It is still a further object of the invention to provide an apparatus for placing dice in temporary packages wherein the packages are supported on carriers such as boats or trays that are conveyed along a path through a predetermined assembly/diassembly position. A carrier preferably includes a body portion and at least one side rail having a plurality of spaced openings therein. The carrier may be formed of plastic or metal. The apparatus further includes an indexing mechanism that functions to place each temporary package in the predetermined assembly/diassembly position to allow the integrated circuit die to be positioned precisely therein.
Still another object of the present invention is to provide a method and apparatus which utilizes previously stored die characteristics for a die in a known temporary package and in a known boat to disassemble electrical dice and temporary packages from one another based on predetermined parameters and to classify the die appropriately.
According to more specific aspects of the present invention, an assembly system is provided to place die bond pads in electrical contact with temporary package electrical interconnects. Once the die bond pads are in contact with the electrical interconnects, the temporary package can be placed in a standard device tester and subjected to extensive testing. Such testing includes burn-in testing and the like to establish various die characteristics and eliminate mortality. These characteristics, while not meant to be limiting, include the quality of the electrical contact between the die and the temporary package in addition to classifying the die in the temporary package based on speed grade characteristics.
The method and apparatus in accordance with the present invention includes a system which picks up and places a die on a die inverter. The die is then inverted and placed in view of a rough die camera, which takes a picture of the die. Using positional feedback from the rough die picture, a robot having a primary gripper with a restraining device attached thereto retrieves the die. The die is then presented to a fine die camera by the robot and multiple pictures are taken. While the die is being located by the die cameras, a process carrier containing a plurality of temporary packages is simultaneously indexed to place a temporary package in a predetermined assembly/disassembly position along a conveyor. An electrical socket is then inserted into the temporary package for continuity testing.
A rough temporary package picture is then taken of the temporary package and used to determine a rough location of the temporary package at the assembly/disassembly position. In a preferred embodiment, a laser height sensor may be used to determine the height of the temporary package at the position prior to taking fine package vision pictures in order to keep the camera in focus. A fine temporary package camera is then positioned over the selected electrical interconnects of the temporary package at the assembly/disassembly position and multiple fine temporary package pictures are also taken.
The die and restraining device are then transferred by a primary gripper to the predetermined assembly/disassembly position. The robot aligns the die and temporary package using the fine temporary package and fine die pictures and presses the die, restraining device and package together to form an assembled package.
During the assembly process, the robot preferably drives to a minimum programmed assembly interlocking height and tests the completed assembly for continuity. If continuity is confirmed, the robot then releases the restraining device and die. If continuity is not established, the robot increments to a maximum programmed force setting. If continuity is still not established, the restraining device and die are removed from the temporary package. A new temporary package is placed in the predetermined assembly position and the fine die, rough package, and fine temporary package pictures are retaken. The die and new temporary package are then reassembled and retested.
In an alternative embodiment of the present invention, the robot drives down until physical contact is established between the die and the temporary package. After physical contact is established, the robot drives to a minimum programmed assembly interlocking height. The primary gripper releases the die and lid or other restraining device and retracts to a waiting position. Electrical continuity of the assembly is tested. If the assembly has electrical continuity between the die and the temporary package, the process is completed. If electrical continuity is not established, the primary gripper retrieves the die and restraining device and awaits instruction from the operator. The operator may choose to retry the present temporary package, utilize the next package, or purge the die from the system and use the next die.
Any electromechanical device which is capable of transferring component parts from one position to another may be used in the present invention. In a preferred embodiment, however, the transferring device is a robot arm. The apparatus has a control mechanism including a microprocessor and associated program routines that selectively control the robot arm (i) to move the primary gripper to pick up a restraining device and to a lid feeder station to pick up a lid, (ii) to move the primary gripper along with the lid and restraining device to pick up the die following photographing by the rough die camera, (iii) to move the primary gripper along with the lid and the die to a position to be photographed by the fine die camera, and (iv) to move the lid and the die to the predetermined assembly/disassembly position located along the conveyor.
The control routines also function to return the primary gripper to the predetermined assembly position and retrieve the die and restraining device in the event that continuity is not established with the temporary package. The primary gripper then returns to select a second lid, another restraining device and a second die while the carrier is simultaneously indexed to place the next temporary package of the carrier in the predetermined assembly/disassembly position along the path. The assembly process continues in this manner.
The present invention also includes a method and apparatus for disassembling the electrical die and temporary package based on predetermined parameters or characteristics. The disassembly process occurs in a manner substantially opposite the assembly process. In particular, a carrier containing a plurality of temporary packages approaches the predetermined assembly/disassembly position. Each package contains an electrical die which has been subjected to extensive testing. The primary gripper retrieves the electrical die and inverts the die using a die inverter. A lid precisor similar to the one used for assembly is used to place the lid in a known location. The die is thus separated from the temporary package.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention as will be described. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the following Detailed Description of the preferred embodiment.